Optimizing Water Use Efficiency on Violet and White Garlic Types through Regulated Deficit Irrigation

In a three year research, three garlic cultivars from the ecophysiological group III (Argentine classification) were submitted to regulated deficit irrigation (RDI) at different growth stages to evaluate the response in terms of yield and water use efficiency (WUE). Trials were carried out in San Carlos, Mendoza, Argentina, on fine sandy loam typic Torrifluvent soil. Treatments were distributed in a split plot design and disposed in completed randomized blocks with three replicates. Cultivars were 'Lican INTA' (violet commercial type), and 'Nieve INTA' and 'Union' (white commercial type). Irrigation treatments were assigned to main plots and cultivars to subplots. In R-1, the water requirements (ETc) were 100% replenished during all the season; in R-2, RDI (50% of the Etc) was established during the initial vegetative growth stage; in R-3, RDI was set up during the second fast vegetative growth stage; in R-4, RDI was applied during the bulb growth stage. Soil water content was monitored with a portable probe (Diviner) and watermark sensors at different soil depths. The crop yield response factor (k(y)) was calculated for each growing stage. Yields were differently affected by the irrigation treatments among cultivars. For 'Nieve INTA', the irrigation deficit imposed during rapid bulb growth (R-4) yielded 8.5% less than the R-1 treatment; while 'Lican INTA' and 'Union' were not significantly affected by these treatments. Irrigation deficit at bulbing yielded the highest WUE in all cultivars. The water use was more efficient in all deficit irrigation treatments. The most sensitive stages to the water deficit were the initial vegetative growth (R-2) in 'Lican INTA' (k(y): 0.62), the bulbing (R-4) in 'Nieve INTA' (k(y): 0.47) and the rapid vegetative growth (R-3) in 'Union' (k(y): 0.69).